It is often necessary to install a pitot tube type of fluid flow meter into a conduit while pressurized liquid or gas is flowing in the conduit. Apparatus has been designed to implement this type of installation, including, for example, the Rosemont 485 Annubar® Flanged Flo-Tap Assembly. In making use of this or similar apparatus to insert a sensor into a pressurized fluid conducting conduit it is extremely difficult to determine whether the bluff body sensor portion of the averaging pitot tube is completely inserted in the conduit, that is, inserted diametrically into the conduit so that the distal end of the bluff body sensor is in firm and stable contact with the inside surface of the conduit opposite the point of insertion. If not firmly seated against the wall of the conduit the sensor is subject to breaking. Conversely, the pitot tube sensor can be damaged if the insert-retract mechanism is over tightened during installation. One particular technique of the prior art utilizes colored markings on the sensor to visually indicate the distal end's approach to the far side of the conduit. Such a method however, lacks the finesse necessary to insure proper seating of the sensor or guard against damage during insertion. Another method involves sensing the change in torque applied to the insert mechanism. This method is unsatisfactory because the line pressure in the conduit affects the torque required to insert the sensor probe.
Accordingly, the primary object of the present invention is to establish a method and apparatus that will overcome the aforesaid difficulties encountered in the installation and proper monitoring of the operation of an averaging pitot tube type of fluid flow meter.